This document explains how to back up and restore the complete operational environment of Zaurus PDA. The main advantage over the backup/restore procedure supplied with the device is that the backup archive file is encrypted. This means that even if the data on the Zaurus must be carefully guarded against any unauthorized access, there is no need to guard the backup archive file: it may be, for instance, stored and retrieved from any web-server using insecure, public access or it may be burned on a CD without much concern whose hands that CD might end up in sometime in the future.
Another potentially useful feature of this procedure is that the encryption program works "at both ends": on the Zaurus and on the PC. This means that in an emergency (for instance, if the Zaurus is lost or broken while travelling) the backup archive can be decrypted and de-compressed on any PC. Decrypted archive is a compressed 'tar' file well known to Linux users; if the PC on which the backup archive is decrypted runs Windows, 'tar' program for Win32 platforms can be obtained from http://gnuwin.epfl.ch/ . Wading through the raw Zaurus address-book file in XTML format on a PC might not be the most elegant way to get an address or a phone number, but if it is the only way, one would quickly find it quite tolerable.
The working components of the procedure explained herein are the Burp encryption program for Zaurus and two shell scripts: the first one to backup and the second to restore the device. Both shell scripts are described in this document. The "terminal" application must also be installed on the Zaurus.
This procedure has been tested on Zaurus SL-5500 with Sharp ROM, standard "terminal" application (from the CD that comes with the Zaurus) and FAT-formatted MMC card. It is expected to work with any ROM version and SD/MMC card. Only minor modifications might be required if the backup is stored on CF card. The following assumes that the "terminal" application is installed on Zaurus and that files can be transferred from the memory card to a PC and vice versa.
The steps you will have to carry out are:
Before you do any of the following, ensure you have an up-to-date conventional backup and know how to restore the Zaurus after performing a "hard reset".
Next, copy - using whatever method you normally use to transfer files between PC and Zaurus - the Burp program Zaurus binary from its web repository to the /usr/bin directory on Zaurus. Ensure that it is executable; if necessary consult Linux chmod command documentation for details. Read Burp documentation in (burp.txt file) and test it by ecrypting and decrypting some data files.
Using a text editor that writes clean ASCII text files, create two files, one called "bkopenv" and the other called "rstopenv". These names suggest "backup of operational environment" and "restoration of operational environment". You can change the names of these scripts, rename the encryptor program and use a different name for the directory where the archive will be stored, as long as you consistently change all references to such names in everything that follows.
Copy both scripts to the same /usr/bin directory on Zaurus and ensure they are likewise executable.
The content of the first script ("bkopenv") file is:
#!/bin/bash
cd /
tar -cf /tmp/xx_archive.tar home/*
if [ $? != 0 ] ; then
echo "Error: tar failed"
exit 1
fi
gzip /tmp/xx_archive.tar
if [ $? != 0 ] ; then
echo "Error: gzip failed"
exit 1
fi
burp -eo -c /tmp/xx_archive.tar.gz
if [ $? != 0 ] ; then
echo "Error: burp failed or aborted"
exit 1
fi
mv /tmp/xx_archive.tar.gz /mnt/card/xx_dir/xx_archive.tar.gz.burp
if [ $? != 0 ] ; then
echo "Error: can't move archive to SD card"
exit 1
fi
ls /mnt/card/xx_dir/.
echo "User backup done"
The content of the second script ("rstopenv") file is:
#!/bin/bash
cd /
if [ ! -f /mnt/card/xx_dir/xx_archive.tar.gz.burp ] ; then
echo "Error: no file [/mnt/card/xx_dir/xx_archive.tar.gz.burp]"
exit 1
fi
burp -d -c /mnt/card/xx_dir/xx_archive.tar.gz.burp /tmp/xx_archive.tar.gz
if [ $? != 0 ] ; then
echo "Error: burp failed or aborted"
exit 1
fi
gunzip /tmp/xx_archive.tar.gz
if [ $? != 0 ] ; then
echo "Error: unable to decompress"
exit 1
fi
tar -xf /tmp/xx_archive.tar
if [ $? != 0 ] ; then
echo "Error: unable to restore"
exit 1
fi
rm /tmp/xx_archive.tar
echo "User restore done"
Once all three components are on the Zaurus, open the terminal
and create the backup directory on the SD/MMC card:
mkdir /mnt/card/xx_dir
You are now ready to backup the Zaurus - simply type "bkopenv" at the bash prompt and supply the key or the passphrase when Burp asks you to do so. Once the archive is created, copy it from the archive directory on the SC/MMC card to the PC and store it wherever you would store your important backup data. Remember, the archive file is encrypted and you don't have to worry who might get access to it - no matter how private and sensitive the data you keep on your Zaurus is.
To restore the Zaurus from the archive, ensure the archive file is in the backup directory on the SD/MMC card and run "rstopenv" shell script. A word of caution: since the "terminal" application, Burp program and restore script will not be present on Zaurus if you were forced to perform "hard reset" (or if you are restoring to a brand-new replacement Zaurus) it is a good practice to keep a copy of Burp (Zaurus binary), restore shell script and qpe-terminal...arm.ipk file wherewer you keep the archive itself. Alternatively, you can prepare (and have handy) a conventional, unencrypted backup set of Zaurus that has no user data, just the terminal application installed and both Burp program and restore script present in the /usr/bin directory.
Note that Burp does not verify the correctness of the decryption key - this is intentional, as it provides for higher security. Whatever key or passphrase you type, it will produce some output; however, if the key was not the same as the one supplied during the encryption, the process will fail in subsequent decompression step.
Finally, there are two things that can not be emphasized enough: read the documentation in the burp.txt file and test this procedure thoroughly before you decide to depend on it in an operational setting.